As conventional non-degradable plastics such as nylons, polyethylene terephthalate, polypropylene, and polyethylene, are recognized as the primary cause of environmental pollutions, biodegradable polyesters are materials on the spotlight for environmental protection purposes and the like. The biodegradable polyesters may be prepared by a batch production method or a continuous production method.
In the batch production method, a relatively long residence time at a high temperature is needed to achieve an intrinsic viscosity and a molecular weight of a desired polyester; a partially heterogeneous reaction may occur even in a reactor, and properties of the polyester may be different at the initial, intermediate, and latter stages of a discharge process after the completion of the reaction. In this regard, when the biodegradable polyesters reside at a high temperature for a long period of time, the biodegradable polyesters may hydrolyze due to heat, which may affect mechanical strength and hydrolysis-resistant properties of the biodegradable polyesters and which may cause a quality difference due to the partially heterogeneous reactions and different discharge time.
On the other hand, the continuous production of the biodegradable polyesters has the advantages of inhibiting hydrolysis of the biodegradable polyesters caused by heat that occurs in the batch production method, mass-producing the biodegradable polyesters, and continuously obtaining products with a uniform quality.
When preparing the biodegradable polyesters, diols such as 1,4-butanediol are generally used as aliphatic dihydroxy compounds.
However, there are many rooms for improvements to the current use of 1,4-butanediol because 1,4-butanediol changes into tetrahydrofuran during a reaction and often causes problems in a vacuum line of a manufacturing device, and because an excess quantity of 1,4-butanediol is also needed.